Methods and apparatus for combined variable damping and variable spring rate suspension

ABSTRACT

Pressure-sensitive vales are incorporated within a dampening system to permit user-adjustable tuning of a shock absorber. In one embodiment, a pressure-sensitive valve includes an isolated gas chamber having a pressure therein that is settable by a user.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation of theco-pending patent application, U.S. patent application Ser. No.15/788,711, filed on Oct. 19, 2017, entitled “METHODS AND APPARATUS FORCOMBINED VARIABLE DAMPING AND VARIABLE SPRING RATE SUSPENSION”, byDennis K. Wootten et al., and assigned to the assignee of the presentinvention, the disclosure of which is hereby incorporated herein byreference in its entirety.

The U.S. patent application Ser. No. 15/788,711 is a continuation of thepatent application, U.S. patent application Ser. No. 14/854,805, filedon Sep. 15, 2015, and is now issued U.S. Pat. No. 9,797,467, entitled“METHODS AND APPARATUS FOR COMBINED VARIABLE DAMPING AND VARIABLE SPRINGRATE SUSPENSION”, by Dennis K. Wootten et al., and assigned to theassignee of the present invention, the disclosure of which is herebyincorporated herein by reference in its entirety.

The U.S. patent application Ser. No. 14/854,805 is a continuation of andclaims the benefit of U.S. patent application Ser. No. 14/271,091, filedon May 6, 2014, and is now issued U.S. Pat. No. 9,186,950, entitled“METHODS AND APPARATUS FOR COMBINED VARIABLE DAMPING AND VARIABLE SPRINGRATE SUSPENSION”, by Dennis K. Wootten et al., and assigned to theassignee of the present invention, the disclosure of which is herebyincorporated herein by reference in its entirety.

The U.S. patent application Ser. No. 14/271,091 is a continuation of andclaims the benefit of U.S. patent application Ser. No. 12/717,867, filedon Mar. 4, 2010, and is now abandoned, entitled “METHODS AND APPARATUSFOR COMBINED VARIABLE DAMPING AND VARIABLE SPRING RATE SUSPENSION” byDennis K. Wootten et al., and assigned to the assignee of the presentapplication, which is incorporated herein, in its entirety, byreference.

The U.S. patent application Ser. No. 12/717,867 claims priority to andbenefit of U.S. Provisional Patent Application No. 61/157,541, filed onMar. 4, 2009, entitled “METHODS AND APPARATUS FOR COMBINED VARIABLEDAMPING AND VARIABLE SPRING RATE SUSPENSION” by Dennis K. Wootten etal., which is incorporated herein, in its entirety, by reference.

The U.S. patent application Ser. No. 12/717,867 is acontinuation-in-part application of and claims the benefit of U.S.patent application Ser. No. 12/509,258, filed on Jul. 24, 2009, and isnow issued U.S. Pat. No. 8,869,959, entitled “VEHICLE SUSPENSION DAMPER”by Joshua Benjamin Yablon et al., and assigned to the assignee of thepresent application, which is incorporated herein, in its entirety, byreference.

The U.S. patent application Ser. No. 12/509,258 claims priority to andbenefit of U.S. Provisional Patent Application No. 61/227,775, filed onJul. 22, 2009, entitled “VEHICLE SUSPENSION DAMPER” by Joshua BenjaminYablon et al., which is incorporated herein, in its entirety, byreference.

The U.S. patent application Ser. No. 12/717,867 is acontinuation-in-part application of and claims the benefit of U.S.patent application Ser. No. 12/407,610, filed on Mar. 19, 2009, and isnow issued U.S. Pat. No. 8,894,050, entitled “METHODS AND APPARATUS FORSUSPENDING VEHICLES” by Dennis K. Wootten et al., and assigned to theassignee of the present application, which is incorporated herein, inits entirety, by reference.

The U.S. patent application Ser. No. 12/407,610 claims priority to andbenefit of U.S. Provisional Patent Application No. 61/038,015, filed onMar. 19, 2008, entitled “METHODS AND APPARATUS FOR SUSPENSION VEHICLESUSING MULTIPLE FLUID VOLUMES” by Dennis K. Wootten et al., which isincorporated herein, in its entirety, by reference.

The U.S. patent application Ser. No. 12/407,610 claims priority to andbenefit of U.S. Provisional Patent Application No. 61/157,541, filed onMar. 4, 2009, entitled “METHODS AND APPARATUS FOR COMBINED VARIABLEDAMPING AND VARIABLE SPRING RATE SUSPENSION” by Dennis K. Wootten etal., which is incorporated herein, in its entirety, by reference.

BACKGROUND OF THE INVENTION Field of the Invention

Embodiments of the present invention generally relate to a suspensionsystem for a vehicle. More particularly, the invention relates to adamper operable in conjunction with a pressure-sensitive valve thataffects dampening characteristics of the damper.

Description of the Related Art

Vehicle suspension systems typically include a spring component orcomponents and a damping component or components. Traditionally,mechanical springs, such as metal leaf or helical springs, have beenused in conjunction with some type of viscous fluid based dampingmechanism mounted functionally in parallel. More recently, compressedgas acting over a piston area has replaced mechanical springs as thespring component in some contemporary suspension systems. Damperstypically operate by restricting the flow of working fluid in a chamberhousing to slow the movement of a piston and rod, especially during acompression stroke. Restrictions within dampers are typically preset for“average” use conditions and are not adaptable to varying conditions.

What is needed is a damper valve that operates at a user adjustablethreshold and permits dampening to occur as needed or desired. Such adamper may be “tuned” to anticipate certain road conditions and/or riderconditions, especially with vehicles like bicycles or motor cycles. Whatis needed is a damper tuning function operating in conjunction with agas spring to permit additional characteristics to be added to anoverall suspension system for improved performance.

SUMMARY OF THE INVENTION

Embodiments of the invention generally relate to the use of pressuresensitive valves incorporated within a dampening system to permitadaptive damping of a shock absorber. In one embodiment, apressure-sensitive valve includes an isolated compressible (e.g. gasfilled) chamber having a pressure therein that is settable by a user.The gas in the chamber acts upon a piston surface in opposition toworking fluid acting upon an opposing surface of the valve to affect theopening and closing of the valve in a damper. In one embodiment thepressure-sensitive valve is incorporated into a damper piston. In oneembodiment a closed position of the valve prevents or impedes operationof the damper and with the valve in an open position; fluid is permittedto travel more freely through the piston during a compression stroke ofthe damper. In another embodiment the valve is disposed in a fluid pathbetween a damper and a reservoir for working fluid. In another example,a gas spring Is incorporated to operate with a pressure-sensitive valveand a gas chamber in the spring is in communication with an isolated gaschamber of the pressure-sensitive valve. In another embodiment, apressure-sensitive valve includes a user-settable gas chamber pressureand an opposing separate compressible chamber permitting additional“tuning” of the damper for various road and/or riding conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features can be understoodin detail, a more particular description, briefly summarized above, maybe had by reference to embodiments, some of which are illustrated in theappended drawings. It is to be noted, however, that the appendeddrawings illustrate only exemplary embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

FIG. 1 is a section view of a damper with an “L-valve” disposed thereinand FIG. 1A is a section view of the damper of FIG. 1 showing the“L-valve” in an open position.

FIG. 2 is a section view of the damper of FIG. 1 with the addition of ablow-off assembly and FIG. 2A is a detailed section view of the blow-offassembly of FIG. 2.

FIG. 3 is a section view of the damper of FIG. 1 with the addition of agas spring operable in conjunction with the damper.

FIG. 4 is a section view of a damper with a variation of an “L-valve”disposed in a piston thereof and FIG. 4A is a perspective view of onemovable portion of the valve of FIG. 4.

FIG. 5 is a section view of a damper having a valve in a piston thereof,the valve having a user-adjustable chamber and an opposing isolatedchamber and FIG. 5A is an enlarged view thereof.

FIG. 6 is a section view of a valve disposed in a fluid path between adamper and remote reservoir.

DETAILED DESCRIPTION

FIG. 1 is a section view showing one embodiment of a suspension damper100. The damper includes a housing 110 with a rod 115 and piston 120arranged to move downward into the housing 110 during a compressionstroke and upward back out of the housing during a rebound stroke. Aworking fluid (e.g. damping fluid such as hydraulic oil) 125 in thehousing passes through the piston 120 during each stroke and, dependingupon the dampening needs, is metered to control a rate of movement ofthe piston 120 in the housing 110. A gas filled reservoir 130 at one endof the housing 110 and separated from the working fluid by a floatingpiston 131 provides additional volume as the rod 115 moves into thehousing and displaces the working fluid 125. The gas in the reservoir130 is user-adjustable via a fill valve 133 (such as for example aSchrader or Presta type gas fill valve) mounted externally and in fluidcommunication with the reservoir 130. Eyelets 190 formed at each end ofthe damper 100 permit attachment to various parts of the vehicleallowing them to move relative to one another in relation to relativemovement of the vehicle parts (e.g. wheel and chassis).

In the embodiment shown in FIG. 1, the piston includes an “L-valve” 150(a volume of rotation about the axis of the damper and so named becauseof its I shaped appearance in section) that is designed to open andallow fluid 125 to pass through the piston 120 under certain conditionsduring the compression stroke of the damper 100. The L-valve is shown inmore detail in FIG. 1A.

In one embodiment the valve assembly 150 includes an annularly-shapedmember or valve member 155 including two piston surfaces 160, 170.Surface 160 is exposed to the working fluid 125 of the damper 100 whilesurface 170, having a relatively smaller surface area in the embodimentshown, is exposed to a source of pressurized fluid (e.g. gas) in achamber 180. The pressurized gas acting upon surface 170 is supplied viaa pathway 181 extending through the rod 115 and terminating in auser-adjustable fill valve 183 (such as for example a Schrader or Prestatype gas fill valve). Chamber 180 and hence surface 170 are isolated(including by o-ring seals as shown but not numbered) from the workingfluid 125 of the damper 100. In one embodiment, a constant gas pressureexerted on surface 170 biases the valve 150 to remain in a normallyclosed position because the pressure set in chamber 180 is higher(optionally substantially higher depending on the ratio of areas 160 and170) than fluid pressure in a compression side 127 prior to operation ofthe damper (Le. static or ambient fluid pressure).

In order to open the normally closed L-valve assembly 150, a force F1(not shown), corresponding to a pressure P1—(not shown) exerted on (e.g.multiplied by) surface area 160 (area—A1), must be greater than anopposing force F2 (not shown), corresponding to a gas pressure (P2—notshown) exerted on surface area 170 (A2—not shown). In other wordsF1=P1.times.Area 160 and F2=P2.times.Area 170 and the valve assembly 150will open during a compression stroke when P1.times.Area160>P2.times.Area 170 (i.e. when F1>F2). The areas 160 and 170 as wellas the pressures P1 and P2 are selectable by design and/or in use sothat the valve opening threshold can be adjusted as desired. In oneembodiment, when F1 becomes greater than F2, member 155 is movedupwardly in relation to the piston body and surface 160 of the L-valve,which normally obstructs a fluid path 162 through the piston (see FIG.1A), is lifted off a valve seat 165 permitting fluid 125, during acompression stroke, to move from the compression 127 to a rebound side128 of the damper housing 110. In use, the value of F1 is typicallyincreased dynamically during a compression stroke and results from thedynamic increase in P1 during that stroke. The increase in P1 isproportional to the velocity of the compression. Another factor causingan increase in P1 (and correspondingly F1) is the position of the rod115 within the housing 110. The further into the housing 110, that therod 115 travels, the more volume is displaced within the housing 110 bythe rod 115. Such displacement compresses chamber 130 ultimatelyincreasing the pressure therein and correspondingly increasing thestatic or “ambient” pressure within the fluid 125 throughout The initialpressure charge in chamber 130 also has a bearing on the static anddynamic value of P1 at various times throughout the stroke. In practice,the pressure conditions necessary to open the valve 150 are determinedby the design of the system itself, including the areas of surfaces 160,170, the user-adjustable pressure supplied to chamber 180 and theuser-adjustable pressure supplied to gas reservoir 130.

In one embodiment, the damper valve 150 functions when the piston 120and rod 115 are moved during a compression stroke. Initially, flowthrough the piston is blocked by the seating of surface 160 on valveseat 165 brought about by a downward force (“downward” as shown inFIG. 1) of compressed gas on surface 170. As the compression strokecommences, pressure of working fluid 125 in the compression side 127 ofthe chamber rises (along with a slight drop in the pressure of the fluidin the rebound side) and, partially due to the relatively large surfacearea of 160, overcomes the force exerted by the pressurized gas inchamber 180 and the valve assembly 150 opens. After opening, workingfluid 125 is metered through the piston to a rebound side 128 of thehousing and the damper valve 150 operates to control velocity of thepiston 120 and rod 115 as it moves downward in the housing 110. In FIG.1, the L-valve 150 is a one-way valve permitting fluid to flow only inthe compression stroke of the damper. While not shown in the Figure,return flow during the rebound stroke is typically provided by aseparate fluid path and any metering necessary may be accomplished in anumber of ways. In one embodiment, return flow occurs through dedicatedorifices (not shown) that include check valves that block flow from side127 of the piston to side 128 while allowing flow in the reverse. In oneembodiment, the use of shims can keep a fluid path (including a returnflow path) closed or restricted until a predetermined pressure or flowrate is achieved. In one embodiment shims are positioned underneath theL-valve 155 between surface 160 and 165 so that the L-valve keeps theshims from flexing until the valve assembly 150 opens at which time theshims may then flex to meter fluid through the piston during compressiondamping. FIG. 1A shows the L-valve 150 in an open position andillustrates the flow of working fluid 125 through flow path 161 (withthe flow path shown by arrow 162) and into the rebound portion 128 ofthe chamber as the piston and rod move down in the compression stroke.

In addition to the simple arrangement of FIGS. 1 and 1A, the L-valve canbe used with additional components in order to make dampening moreadjustable or more responsive to road or driving conditions. FIG. 2 is asection view of a damper similar to the one of FIG. 1 with the additionof a “blow off assembly” 200 in the damper housing 110. As with thedamper of FIG. 1, the damper shown in FIG. 2 includes a piston 120 androd 115 with an I-valve 150 disposed in the piston. Working fluid 125 inthe damper causes the valve 150 to open when, as previously illustrated,an F1, in the compression 127 side of the housing 110, exceeds an F2exerted on surface 170. In addition to metering of the fluid 125 thattakes place during the compression stroke when the valve is open, fluidis also metered through a blow-off assembly 200 shown in detail in FIG.2A.

In one embodiment the “blow off assembly” 200 includes threesubcomponents: a check valve 205; an adjustable orifice 210 and; anormally closed, spring actuated blow-off valve 215. The check valve 205blocks the flow of fluid from above (i.e. 127) the assembly 200 to belowthe assembly 200, during a compression stroke while permitting the flowof fluid through the assembly, from below to above, during a reboundstroke. The adjustable orifice 210 is provided as another meteringdevice in lieu of or addition to the L-valve 150 to provide additionaldampening during the compression stoke. In one embodiment flow throughthe check valve 205 is metered by shims in the flow direction (not thecheck direction). In one embodiment flow through the orifice 210 ismetered in one or both directions by shims. In one embodiment the checkvalve is checked and metered by a same set of shims. The blow-off valve215 is also a one way valve operable during the compression stroke butis biased toward a closed position by a resilient member, such as forexample in this case, a spring 217. The blow-off valve is designed tooperate only in the event of a relatively high pressure spike, inchamber 127, during a compression stroke of the damper that is createdwhen a “choke” condition arises as fluid is metered through the L-valve150 and the adjustable orifice 210. A choke condition most often arisesdue to fluid flow created by relatively rapid movement of the piston 120and rod 115 in the damper housing 110.

In one embodiment, the size of orifice 210, the initial pressure inchamber 130 and the pressure P2 in chamber 180 are set (and the areas170 and 160 are correspondingly tailored) such that upon initialmovement of the suspension in compression, fluid travels from above tobelow assembly 200 through the orifice 210 while valve 150 remainsclosed. When the piston (including valve 150) has traveled sufficiently,pressure in chamber 127 is increased (due to compression of the gas inchamber 130) and valve 150 opens thereby allowing fluid to flow frombelow to above the piston along path 162. In one embodiment, theforegoing parameters are adjusted such that both valve 150 and orifice210 allow fluid flow substantially simultaneously during compression. Inone embodiment, blow off valve 217 is set to allow excess fluid to flowfrom above the assembly 200 to below when pressure in chamber 127 isincreased dramatically (such “blow off” thereby reducing the pressure inchamber 127) and beyond the flow rate capabilities of other dampingvalve mechanisms within the damper. In one embodiment the blow off valve217 comprises one or more shims.

FIG. 3 is an embodiment of a damper with an L-valve 150 and includingthe addition of a suspension gas spring. Gas springs and their operationare disclosed in Patent Application No. U.S. 2009/0236807 A1, assignedto the assignor hereof and that application is incorporated by referenceherein in its entirety. Similarly to the damper of FIG. 1, theembodiment of FIG. 3 includes a piston 120, rod 115 and L-valve 150 formetering of working fluid, along with a compressible chamber orreservoir 130 and floating piston 131 to compensate for the area of therod 115 entering the housing. Gas springs operate with a compressiblefluid, such as air or some other gas to provide resilience or“springiness” to a suspension system. Unlike a simple and constantlywound helical spring, the force (corresponding to pressure acting on apiston area of the suspension spring piston) versus the linear travel ordisplacement of a single chamber gas spring is not linear. For example,a gas pressure compression curve approximates linearity during aninitial portion of travel but then rapidly becomes exponential and a gassprung shock absorber typically becomes increasingly rigid in at leastthe last ⅓rd of its stroke. In FIG. 3, a gas spring 300 includes anupper enclosure 305, a seal 310 and a seal (not numbered) in housing 110surrounding rod 115, all enabling a gas chamber 315 in the enclosure toremain sealed as the enclosure 305 moves axially with the rod and pistonrelative to the damper housing 110 to compress gas in the gas chamber315 during a compression stroke. Notably, the gas chamber 315 in theembodiment of FIG. 3 is in fluid communication with the chamber 180 viaa fluid path 301. Therefore, like chamber 180, the gas spring isinitially adjustable by a user via fill valve 183 and the gas in bothchambers 180, and 315 will increase in pressure as the gas spring 300compresses during the compression stroke of the shock absorber andcorresponding damper 100. In one embodiment the gas spring 315 comprisesa multi-chamber gas spring system (optionally staged by communicationvalves). In one embodiment the gas spring 315 comprises a suitablecombination of mechanical and gas springs.

In one embodiment the initial fluid pressures and piston areas areconfigured so that a shock, such as is shown in FIG. 3, is initiallycompliant. For example, the pressure P2 within chamber 315 is set toprovide a relatively “soft” spring (compliant vehicle ride) through acertain initial percentage of the compression stroke of the shock (e.g.50%). During the initial compression, F2 is relatively light incomparison to F1 (based partially on the pressure in chamber 130). Suchconfiguration results in a relatively compliant gas spring combined witha relatively low resistance damper. Once the spring reaches a point inits travel (e.g. beyond for example 50%) where the compression pressurecurve for the gas 315 becomes exponentially increasing, thecorresponding pressure P2 in chamber 180 and force F2 becomeexponentially increasing while the pressure in chamber 130 continues toincrease substantially linearly. The result is that both the gas springand the piston damping become increasingly (exponentially) “stiff”during the second half of the compression stroke. Such a configurationallows for a shock system that is very compliant over light to moderateterrain yet very resistant to bottom out over extreme terrain or whenlanding large jumps.

The arrangement of FIG. 3 can provide the benefits of both a gas springand a damper and is operable in a number of ways depending on roadconditions and pre-settings. As illustrated, in one embodiment, theshock of FIG. 3 may provide an initially soft ride to minimize theeffect of small bumps on the surface of a road or trail. As theseverity/magnitude of the bumps increase and more of the compressionstroke is needed, the shock absorber becomes increasingly stiff,effectively adding dampening characteristics (In addition to thestiffening spring) to slow the operation of the damper and avoid abottom-out position. The gas spring causes the shock to reserve sometravel in the case of an additional “bump event” at a time when theshock would otherwise be completely compressed due to gravitationalforces. In other words, the shock embodiment described in reference toFIG. 3 herein may also provide resistance to “g-out” During an encounterwith a long duration low frequency terrain feature, such as a longu-shaped valley, a suspension (particularly a compliant one) damper mayslow bleed through a portion or all of its compression stroke. When thathappens, the shock may be left with little remaining stroke to accountfor subsequent terrain features (i.e. the shock will slow bleed tobottom out). In one embodiment hereof the position dependent rigidity,based on the compression of the gas spring of FIG. 3, that shock may beconfigured to resist g-out due to increased rigidity as a function ofcompression stroke position. While the embodiment of FIG. 3 illustratesa gas spring in conjunction with the pressure sensitive valve, the gasspring may be replaced with a coil spring or any other type of devicehaving a non-linear compression curve. Further, the shock of FIG. 3 mayinclude the blow off assembly of FIG. 2A or any of the valves shown inFIG. 4, 5 or 6.

In certain embodiments hereof, other valves could be used instead of, orin addition to, the “L-valve.” For example, U.S. Pat. No. 5,190,126shows a valve having a user adjustable chamber with pressurized gas.Rather than having the chamber at a location where it urges the valve toa dosed position, the valve incorporates a chamber at a location thatreduces, rather than increases the force needed to open the valve. Thevalve of the '126 patent may be adopted for use in any suitablearrangement hereof and that patent is incorporated by reference in itsentirety herein.

FIGS. 4 and 4A illustrate another type of valve disposed in a damperpiston; one that is pressure-sensitive and operates in many respects asthe L-valve shown in FIGS. 1-3. In the embodiment, referring to FIG. 4,a piston 420 includes an L-valve 450 having an axially movable,annularly-shaped member 456 sealed in the valve housing with sealmembers 459 and having a number of individual members 457 (collet-typefingers, for example) extending from a lower end thereof through thepiston body 420. FIG. 4A is a perspective view of member 456 of FIG. 4.

In FIG. 4, the valve 450 is shown in an open position with the flow offluid through the valve shown by arrow 462. Like the previouslydescribed valves, the valve of FIG. 4 includes a chamber 180, thepressure of which is user-adjustable via a fluid pathway 181 and a fillvalve 183. Gas in chamber 180 acts upon a surface 470 of movable members457 to urge a footed portion 458 of each member 459 away from a seatedposition against a lower end of each corresponding fluid path 460. Inone embodiment, the valve is biased normally open but tends to close asfluid 125 passing through paths 460 during the compression stroke, actson the footed portions 458 of each member 457 and urges them upwards andinto a seated position with a lower surface of the fluid paths 460, As,during a compression stroke, the dynamic pressure builds below each“foot” 458, due to fluid “rushing” toward each corresponding orifice460, each foot and hence the entire valve 456 is urged upwardly againstthe preset pressure in chamber 180. When the compression stroke is fastenough, the dynamic lower pressure, induced by flow through orifices460, will create a force due to the pressure acting over each foot andwill urge the valve toward a closed position. The net result is that thevalve of FIG. 4 can be configured as a velocity dependent valve wheredamping is increased only at selected compression velocities above apredetermined threshold (which is based on the pressure in chamber 180).

FIGS. 5 and 5A illustrate another valve design, also installed in adamper piston 520. The valve operates much like the aforementioned“L-valves” except that it includes an additional compressible (e.g. gasfilled) chamber 585 acting over area 586 in contravention to thepressure in chamber 180 over the upper area (e.g. 170). In oneembodiment the valve 550 includes an axially moveable member 557 that issealed in the piston housing. Member 557 includes a lower surface 590constructed and arranged to seat on a valve seat 595 to block a fluidpath 596 formed in the piston 520. In one embodiment and like the valvesin the other embodiments, the valve 550 may include a user adjustable,isolated chamber 180 at an upper end thereof arranged to act upon anupper surface 570 of the member 557. Additionally, another isolatedcompressible chamber 585 (in one embodiment a closed pre-set volume ofgas such as atmospheric pressure gas), optionally at atmosphericpressure, acts in an opposing manner on a surface 586 of member 557. Apurpose of having the chamber 585 at atmospheric pressure is to ensure apiston area acted upon by a pressure lower than any other pressure inthe damper system thereby more easily biasing the valve to a normallyclosed position. In the embodiment of FIG. 5, chamber 585 is designed toassist the valve in closing, rather than in opening but an oppositeeffect is possible simply by presetting the chamber to a pressure higherthan the pressure of the control fluid in chamber 180 (e.g. higher thanchamber 180) before a compression stroke. In one embodiment the valve ofFIG. 5 operates substantially independently of the gas pressure inchamber 130 and the corresponding ambient pressure of the working fluid.As such the pressures in chambers 180 and 585 can be adjusted as desiredto achieve a balance on the static bias of the valve (including a static“neutral bias—neither open nor closed). The static biasing configurationis offset upon induced motion whereby the dynamic flow of fluid throughthe piston creates a dynamic force (flow induced pressure) on thepressure that changes the net force resolution on the valve 557. In oneembodiment, the valve of FIG. 5 may be neutrally balanced in a staticcondition by equating the pressures in chambers 180 and 585. In oneembodiment such a configuration is placed within the shock of FIG. 3such that the air spring pressure 315 communicates with chamber 180. Asthe shock moves further into compression, the neutral initial balance isdisplaced by an increasingly strong valve closing bias. In oneembodiment the pressure in chamber 180 is set initially higher than thepressure in chamber 585 resulting in an initial closure bias. In oneembodiment the pressure in chamber 180 is initially set lower than thepressure in chamber 585 thereby biasing the valve initially open. Theaforementioned F1 and F2 calculations are, in principle, applicable tothis valve regarding opening threshold provided that F1 is a sum of thepressure in chamber 585 times the area 586 and the working fluidpressure (with its static and dynamic components) over any net areadifference between areas 586 and 170.

In some embodiments as shown in the FIGS. 5, 5A, the valve is shown inan open position with the flow of fluid through path 596 shown by arrow597. By “tuning” the chamber 180 and the presetting isolated chamber585, operation of the valve 550 and therefore the damper 100 can bepre-determined for certain conditions. For example, the addition of thepreset chamber 585 effectively reduces (optionally to zero depending onthe area ratios chosen) the piston area acted upon by working fluid 125as the damper is compressed. By reducing the net area acted on upwardlyby the working fluid during compression, opening of the valve can berelatively retarded. In one embodiment, the pressure-sensitive valve canbe equipped only with a sealed atmospheric chamber or a sealed chamberof any pre-settable pressure. Such chamber can be located at either“end” of the valve permitting it to affect operation in any number ofways as it eliminates a portion of a piston surface that would otherwisebe acted upon by working fluid in the damper.

The pressure-sensitive valves disclosed herein need not be incorporatedin or even adjacent a damper piston but can be remotely located in anyfluid path between a damper chamber and a reservoir. FIG. 6 is a sectionview of a pressure-sensitive valve 650 disposed not in a piston, but ina fluid path 651 between a damper chamber and a remote reservoir (notshown). Remote reservoirs provide the same function as the reservoirshown in FIG. 1, but consist of a separate housing and chamber. Remotereservoirs are shown and explained in U.S. Pat. No. 7,374,028, which isincorporated by reference herein in its entirety. In the arrangement ofFIG. 6, the valve 650 includes a housing 652 with an axially moveablemember 655, sealed in the housing and including a flange 660 constructedand arranged to seat and unseat on a seating surface 665 formed at alower end of the valve body 652.

In one embodiment the valve of FIG. 6 includes a chamber 680 that is incommunication with ambient air pressure through a pathway 682. Any valveconfiguration described herein may be suitably used to control flowbetween a chamber and a reservoir. In one embodiment the valve of FIG. 6is not mounted in a damper piston and does not move with the piston, andit tends to operate in a position-sensitive manner while being minimallysensitive to velocity of the piston. For example, in the Figure thevalve is shown in an open position with fluid flow shown by arrow 680.As the piston and rod move into the chamber (not shown) in thecompression stroke the corresponding pressure developed by the floatingpiston and gas-filled reservoir (not shown) will increase pressure ofthe working fluid acting on surface 677. In this manner, the velocity ofthe piston and rod have reduced bearing on the operation of the valve,while the position of the piston and rod are largely determinate of thevalve's position.

As shown in the description and Figures, embodiments permitpressure-sensitive valves to be incorporated into and/or used inconjunction with fluid dampers to provide various means for a user totune a damper based on dynamic road conditions. In some embodiments, thepressure-sensitive valve is urged to a closed position to increasedampening in the shock absorber. In other instances, the valves areurged to an open position to permit fluid to flow between thecompression and rebound sides of the chamber in order to decreasedampening. In some embodiments the valve is incorporated in a pistonbetween a compression chamber and a “rebound” receiving chamber and inother embodiments the valve is incorporated between a compressionchamber and a “reservoir” receiving chamber. Either of the reservoirchamber and the rebound chamber (and any other suitable chamber) enabledamping by receiving working fluid from the compression chamber during acompression stroke.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What we claim is:
 1. A vehicle suspension damper comprising: a cylinder;a piston assembly comprising a piston and piston rod within saidcylinder; a remote reservoir, said remote reservoir having a housingseparate from said cylinder, said remote reservoir fluidically coupledto said cylinder via a pathway, said remote reservoir comprising: afluid chamber; a gas-filled reservoir; and a floating piston movablydisposed between and fluidically isolating said fluid chamber and saidgas-filled reservoir; and a pressure-sensitive valve disposed in saidpathway, said pressure-sensitive valve configured to adjust damping ofsaid vehicle suspension as a pressure change occurs within saidcylinder, said pressure-sensitive valve further comprising: a movablemember, said movable member having a surface, said surface of saidmovable member exposed to said cylinder; and a plurality of footedportions coupled to said movable member, each of said plurality offooted portions having a surface, said surface of each said plurality offooted portions exposed to said fluid chamber of said remote reservoir,each said surface of said plurality of footed portions having an areagreater than an area of said surface of said movable member, saidpressure-sensitive valve having a closed position wherein said movablemember is disposed such that said plurality of footed portions obstructfluid flow through said pathway.